Lathe question?

dubtom

I have two lathes, a draper and a variable speed Delta. Both have 3/4 hp motors. I've had the draper a few years and it's served me well but I have been trying to turn a solid beech platter off the bed, it's 15' in diamater, and the lathe is set at 500,(if I set it any higher I'm afraid the whole thing will take off)
it's proving to be a chore. The lathe grinds to a halt when I put a gough near it,as if their is no power in the motor, and then climbs slowly back to speed, I'll be here untill xmas just trying to round the wood.I should add I cut the wood on the bandsaw as round as I could get it.The draper is not big enough to accept the 15' or I'd try it on that. Whats your expierence with turning large pieces off the bed,is your lathe a bigger capacity hp wise.I will probably be forced to turn up the speed to 850 and see if that works,but it doesn't seem safe tbh.

charlesanto

How about mounting a router on the bed of the lathe.
Take the lathe outta gear so that you can spin the chuck freely.
Adjust the position of the router 'til you've a nice regular shape ...
Then back to conventional turning at high revs !!!

Alun

dubtom wrote:

I have two lathes, a draper and a variable speed Delta. Both have 3/4 hp motors. I've had the draper a few years and it's served me well but I have been trying to turn a solid beech platter off the bed, it's 15' in diamater, and the lathe is set at 500,(if I set it any higher I'm afraid the whole thing will take off)
it's proving to be a chore. The lathe grinds to a halt when I put a gough near it,as if their is no power in the motor, and then climbs slowly back to speed, I'll be here untill xmas just trying to round the wood.I should add I cut the wood on the bandsaw as round as I could get it.The draper is not big enough to accept the 15' or I'd try it on that. Whats your expierence with turning large pieces off the bed,is your lathe a bigger capacity hp wise.I will probably be forced to turn up the speed to 850 and see if that works,but it doesn't seem safe tbh.

Firstly, I assume you mean 15" (inches) and not 15' (feet)!

Anyway, 500rpm should be plenty fast enough at the perimeter of a piece that size, I'd say. Is the motor actually stalling, or is the belt (does the draper have a belt?) slipping?

Even though you're starting off with a nominally 'round' piece of wood, and also because even if you're really careful you'll never get it exactly centered on whatever you're mounting it on, the first few rounding off cuts will be cutting alternately wood and air, so you have to be really careful you don't dig in the tip of the gouge. Try going back to basics and holding the gouge with the handle well down and very slowly bringing it up until it cuts. Also try tilting the gouge slightly to one side and moving across the wood rather than holding it perpendicular to the wood if you see what I mean. Once it's rounded off you should be able to get a bit more aggressive with the cuts without digging in.

The trick with the router mentioned above is a handy one, but only really for very big out of round pieces. Shouldn't be necessary for something that size.

dubtom

Thanks lads for the replies.I'm not sure if the belt is slipping Alun, I retighten the motor bolt and the belt seems tight enough. I've upped the speed to 850 and it's still slowing down on contact but I'm managing to remove a bit more each time.My technique,although probably a bit corse at the best of times,:) I don't think is at fault on this one. I'm getting there slowly anyway. I suspect that 3/4 hp off the bed is underpowered, I've never had a problem like this between centers that a little tailstock adjustment would fix.

dubtom

Just an update lads. I discovered my face plate isn't straight,as in the face has a slight concave on it, the treads seem a bit off too which might explain why the lathe vibrates so much at anything above 500. I've wondered why it was always so difficult to turn a bowl that wasn't slightly off:rolleyes: A guy in Mcquillans,where I bought a new faceplate,rekoned the power source could be the problem with the lathe slowing down all the time,which actually makes sense, I've been using an extension cable recently because some of the sockets in the shed aren't working, so it may be the reason. I'll just have to find the offending socket on the loop and fix it now,I've been putting it off for ages.

Alun

dubtom wrote:

A guy in Mcquillans,where I bought a new faceplate,rekoned the power source could be the problem with the lathe slowing down all the time,which actually makes sense, I've been using an extension cable recently because some of the sockets in the shed aren't working, so it may be the reason. I'll just have to find the offending socket on the loop and fix it now,I've been putting it off for ages.

Yes, a long extension lead can cause loss of voltage due to the voltage drop across the cable and therefore a loss of power. A heavy duty one designed for the purpose, with heavy gauge cable will give fewer problems due to the lower voltage drop. Glad you found the problem.

kadman

Slide up the tailstock to the blank , to support it while you are turning it symmetrical. I t will steady it for you, if you have the room to work with it close up to the head stock.

kadman

geofftulip

the stalling problem you are having is almost certainly your motor - i'm afraid it just cant turn that sort of size unless it is very dry and light and only 1-2" thick.
you may have simply reached the limits of your lathe.

if you have to turn the piece - you are welcome to come up turn it on my lathe if you wish....

dubtom

Your right Geofftulip, I over estimated the size of the motor in a previous post,it's actually only a 1/2 HP,370W. I had looked at upgrading it, could get a 1 or 2 HP motor for 100-140 euro but changing over would be as expensive as a new lathe. I dropped into Mcquillans yesterday and they have the record cl4 for 1200 quid, 1 Hp with a fancy single to 3 phase adapter that aparently gives a smother,with more torq turn, and turns 30 + off the bed to booth.Not sure if I can justify that cost for a hobby though. Thanks btw for the offer, very nice of you. My platter can wait for a while;)

dubtom

:rolleyes:

geofftulip

the record lathe is a good lathe - to me it is still a hobby lathe - for the same money look around for a good old strong lathe - this way you will get a lathe that you wont reach the limitations of very quickly. perhaps a graduate or as i have done the wadkin rs - they are a supreme bit of engineering and as solid as only an old bit of kit can be - with some extras that no modern lathe provides. for the same money you can buy a wadkin - replace the motor with up to 3hp and have variable speed. you wont outgrow it - guaranteed...
for pics - check out ebay the the moment - there are 2 for sale - they generally go for about £500. with a bit extra for transport - if you wish to see one in person you are welcome to call up and check mine out ....

geofftulip

one other point i forgot to mention ( by the way i like the record lathe and have had one myself )- manufacturers of lathes with swivel heads often say they can turn 30" off the bed - in my experience that is not the whole truth - the 30" would need to be thin, of very dry wood, and perfectly round before they should be mounted on the lathe - a lathe with set pulleys will lift the lathe off the floor if you start them with an off round 'normal' piece of wood. in - even variable speed lathes with swivel heads do not have the frame or the power to turn 30"+ pieces of wood that are anything other than planks -

maybe other turners who have swivel heads can help out here and state the biggest diameter, depth, mass and type of blank they have turned on the swivel head - might prove me wrong !!!!

dubtom

I actually looked at Graduate's Geoff but didn't get a price on one (although I did see a add for upgraded motors with variable for 500 sterling, just for the upgrade) a bit out of my league. Those few on ebay look the biz ok, pity their in the UK.I haven't fully commited to the record, may wait untill after xmas when my ss comes in.Thanks for the info and invites.

Alun

I have a swivel head on my Nova 3k, but to be honest I don't really use it to be able to turn pieces larger than I could over the bed, but more to be able to better get at the pieces when hollowing and save my poor aching back, especially if they're a bit on the deep side. At that stage most of any imbalance that's present has been removed anyway. About 15" is my limit so far .. turning something as big as 30" would scare me half to death

dubtom

Nova 3K, what model is that Alun? Is 3k a model number or 3hp motor?

Alun

dubtom wrote:

Nova 3K, what model is that Alun? Is 3k a model number or 3hp motor?

Sorry, it's just lazy shorthand for a Teknatool Nova 3000 Only a 1HP motor, but plenty enough for me at the moment. I'd quite like it's big brother, the Nova DVR XP, but that'll have to wait for another day.

geofftulip

the nova is a very good lathe and is in a differnt league to the record etc....
there is a guy local to me who sells upgraded graduates - very expensive though 2k + ...... there is also a wadkin rs for sale by a man local to me who has been chasing me for ages to buy it - i would take it but as alun knows i dont have the space for two of the beasties.....£600 i think he wanted but would take a further 300 for the upgrade to variable and 3hp....

dubtom

Sounds attractive geoff, unfortunatly transporting it down to dublin might be a problem and then getting it through my house:rolleyes: 300 sounds like a reasonably price for the upgrade though,does a local guy to you do it.
Oh, and just how big is the wadkin?

geofftulip

they are quite big but thats what makes they so strudy - the upgrades however are quite simple really - i have now done four of these for my own lathes and for others - you are simply dumping your old motor and replacing it with a new 3 phase motor - these generally cost £70-100 for 1-3hp - i used abb motors but others may be suitable - on top of this you need to buy the invertor which converts the single phase to 3 phase for your motor. the invertor needs to match the motors hp. you may aswell go big rather than small at this stage - the invertor will cost 2-300 - (abb again) but there are cheaper ones out there and you may get a second hand one. the invertor is completely programmable and can be wired with start / stop, forward reverse, emergency stop, there are also hundreds of other capabilities but you wont need them -
that is all you need - the rest is a bit of wire , a couple of knobs, swap the pulleys and mount the motor -
if you read into invertors you will hear others say they still swap the belts to give max torque and to keep the motor running at high revs whhich helps it cool - this may be true but in prcatice i turn some immense pieces at low speed and often sand for ages at low speed and have never had a problem (if you are worried you can fit a cooling fan to the motor cowl) - i keep the belt on say pulley 2 of 4 and never change it - your top speed may be less than normal but this really isnt an issue for me.....the speeds can be worked out from the pulley ratios if you are worried -

if you any other info or want to see it in action call up...

by the way - one other bonus is that you can buy lots of big old 3 phase machinery (which is alot cheaper) and run them of the invertor aswell -